Help with Email Class

Hi, community!

This is my first topic.

I have a problem, I'm try to send a email for some users of my system that is based on CI 3.1.11 and the source html of the email is displayed. This is the configurations that I use at this moment:

$config['protocol']    = 'sendmail';
$config['mailpath']    = '/usr/sbin/sendmail';
$config['charset']    = 'utf-8';
$config['mailtype']    = 'html';
$config['wordwrap']    = TRUE;
$config['smtp_host']  = '****';
$config['smtp_user']  = '****';
$config['smtp_pass']  = '****';
$config['smtp_port']  = '25';
$config['smtp_crypto'] = 'tls';

Test message:
<center>
<table border="0" width="100%" cellspacing="0" cellpadding="0" align="center">
<tbody>
<tr>
<td style="padding: 20px;" align="center" valign="top">
A
</td>
</tr>
<tr>
<td style="padding: 20px;" align="center" valign="top">
B
</td>
</tr>
</tbody>
</table>
</center>

But is displayed like it:


How I can solve it? Thank you!